1. Field
Example embodiments relate to a method of forming a contact structure and a method of manufacturing a semiconductor device having a contact structure. More particularly, example embodiments relate to a method of forming a contact structure including a metal oxide silicide layer and a method of manufacturing a semiconductor device having the contact structure.
2. Description of the Related Art
As for a volatile semiconductor device or a nonvolatile semiconductor device, a metal silicide layer generally is formed between a contact region of a substrate and a contact or a plug in order to reduce the resistance of the contact or the plug. After performing a silicidation process in which silicon included in the contact region of the substrate is reacted with metal included in a metal layer, the metal silicide layer is formed between the contact region and the contact, so that a contact resistance or an interface resistance between the contact and the contact region may be reduced.
To effectively form the metal silicide layer on the contact region, a cleaning process is carried out to remove a native oxide film or other insulating materials from the contact region, and then the metal layer is formed on the cleaned contact region.
FIG. 1 is a cross-sectional view illustrating problems of a conventional process for forming a contact in a semiconductor device.
Referring to FIG. 1, in the conventional process for forming the contact, an insulation layer 3 is partially etched to form a contact hole 5 exposing a contact region of a substrate 1 after forming the insulation layer 3 on the substrate 1 having the contact region (not illustrated).
A native oxide film (not illustrated) generated on the contact region exposed by the contact hole 5 is removed. The native oxide film may be removed from the contact region by a cleaning process using a solution including hydrogen fluoride (HF).
After a metal layer 7 including titanium (Ti) is formed on the contact region, a sidewall of the contact hole 5 and the insulation layer 3, the silicidation process is performed about the substrate 1 having the metal layer 7, to thereby form a metal silicide layer 9 on the contact region. When the metal layer 7 includes titanium, the metal silicide layer 9 includes titanium silicide (TiSix).
As for the conventional process for forming the contact, however, the metal silicide layer 9 may not be uniformly formed on the contact region because the silicidation process is executed after removing the native oxide film from the contact region. That is, the metal silicide layer 9 may be irregularly formed or grains in the metal silicide layer 9 may be agglomerated due to process conditions of the silicidation process such as a process temperature, a process time, etc. Further, the metal silicide layer 9 may not have a desired thickness on the contact region, and also voids may be easily generated between the contact region and the metal silicide layer 9. Particularly, as shown a portion “I’ in FIG. 1, a void may be easily formed between the substrate 1 and the metal silicide layer 9 during the silicidation process because of migrations of metal in the metal layer 7 and silicon in the substrate 1, and also the metal silicide layer 9 may not be properly formed on the contact region with a uniform thickness. Furthermore, an undesired layer 1 having an irregular composition may be easily generated formed on in the metal silicide layer 9. When the contact is formed on the irregular or agglomerated metal silicide layer 9, the interface resistance between the contact region and the contact may not be desirably adjusted to thereby deteriorate electrical characteristics of the semiconductor device having the contact.
Considering the above-mentioned problems, Korean Laid-Open Patent Publication No. 2005-2995 a method of manufacturing a semiconductor device having a double layer structure including a native oxide film and a cobalt silicide layer can be formed between a substrate and a polysilicon plug without removing the native oxide film.